Small texture cannot be clipped in Material Viewport Shading, always repeats
As far as I know OpenGL viewport preview doesn't support texture clipping options, so they will always display tiling infinitely.

Also viewport material preview is quite limited, it is meant as a reference only.

They should render properly when pressing the F12 key regardless of render engine, though, except of course OpenGL renders.

Also see How do I Make a Transparency to Decal my Object? (Blender Render Only)